Supercharger finally fitted - PeachParts Mercedes-Benz Forum

MDMB69 · #1 01-17-2006, 03:56 AM

My supercharger project was completed almost at the weekend.
An Eaton M45 blower on to my 2.8 M104 engine. The fabrication although time consuming was relatively simple, the vacuum lines were a bit more of a headache. I have the Apexi fuel controller thanks to Blown_M104's recommendations. My blower came straight from a Mini cooper S although I found that the standard pulley was too small so I fitted it with a 19% smaller pulley. I also kept the silicon hoses down to a minimum becuse the pipes were bursting off under boost. I only getting 4.5psi at the moment but I plan to machine down the pulley to get the 6.5psi I ideally want.
Thats all the good news. Now the problems.
There is some popping and possible blow back I can hear from the engine now when I put my foot down after coming to a stop. Maybe the bypass valve isn't opeing fully, I have checked and it seems to be working but maybe the spring in it is still too strong.
But the biggest problem and here is where I need some advice if anyone can give it. The noise! The supercharger can be heard spinning from 200 yards away, its stops people in their tracks as they stop and stare.
I have read that most manufacturers put tuned induction pipes before the blower to prevent this, but have just the K&N. I've checked the oil in the blower casing & its okay. The blower when turned by hand moves freely but not loosely and not quitely, does anyone else know if the M45 blower is supposed to turn quietly and freely. As it is I've now took the whole thing off till I can sort the noise problem out because its embarrasing to drive. I figure I need a new supercharger or maybe just a normal airbox to deaden the sound.

Brian Felts · #2 01-17-2006, 01:31 PM

I had a version of the Eaton on my 1997 GTP I once had and it was very quiet. Is the noise you hear a metallic or air noise. You may have a bearing going to fail.

Could you post how you mounted the S/C to the motor and other little ins and outs. I would love to make this project on my 3.2 M104

Thanks
Brian

Blown_M104 · #3 01-17-2006, 01:44 PM

Congrats on getting your pulley installed and best of luck with the noise. I've updated my Apexi unit settings quite a bit since we last talked. I'm now in the +35 to +50% range from 1600 rpm though redline with the 5 Bar FPR. Your engine requirements may be different but your probably going to need more fuel.

boneheaddoctor · #4 01-17-2006, 02:04 PM

check your exhaust with a wideband sensor.....make sure its not too lean or you risk serious damage to your engine....

MDMB69 · #5 01-18-2006, 05:16 AM

I've just fitted a new lambda sensor and I have a meter showing me the fuel mixture as i can adjust it with my Apexi. I attached a couple of pictures showing the 2 brackets I had made to mount the charger. It was the inlet and outlet manifolds to the charger that were more complex.
I have last night been fiddling with the charger. I think after all that the charger is okay, both ends have oil in the gear chambers and it does turn quite smoothly when turned by hand, more so now its been run for a long while on the car. I think its definately the air you can hear being pumped out that's causing the noise and not a mechanical noise. I have reseached on the web and many people complain of supercharger noise even on brand new cars. Maybe I'm expecting too much, after having a whisper quiet Merc I'll have to accept the blower will make it noisy. I may add an additional mechanical by-pass valve to open on closed and slightly open throttle. The Bosch bypass valve I have has 22mm bore but when open under vacuum conditions it only fully opens 5mm. This equates into an opening area of 345mmsq against the cross section area of the pipe of 380mmsq. I believe the 2.7 S4 Audi's have 2 of these valves so maybe 1 just isn't enough to by-pass the air on idle on my 2.8. This may reduce noise at idle and the popping noise I'm getting as I close the throttle. I'll also try moving the MAF sensor back to before the blower which is where I had it originally but the engine wouldn't idle. I'm going to bolt the whole thing back on and try connecting the original air box just with the bonnet open to see if the noise reduces. If so I might make a new air box with a panel filter and ditch the K&N; I have read these are the worst filters for transmitting noise.

BF_JC230 · #6 01-18-2006, 11:29 AM

my m-90 also screams...i too have a very short runner from the air filter (K&N cone) to the charger - and i too want to resolve this....it does get alot quieter under driving conditions than at idle...but then loud again at boost...

looks great
jake

jhodg5ck · #7 01-18-2006, 06:56 PM

We have a 99 Regal GS in the family w/ an Eaton blower..Very quiet. I know these SC'ers Really need their oil looked after every 20K or so. Unfortunately most of the units out there are neglected. Did you change the oil before you installed the blower?

Jonathan

Jim Villers · #8 01-18-2006, 08:30 PM

Congratulations on getting it running. The M45 might be too small for a 2.8L enging but it will be fun to play with.

I installed an Eaton supercharger froman SLK (M45) in my 2.3-16 and spent about two years sorting out the issues that you describe. My supercharger runs about 6psi and it is also noisy.

From your description, you have a vacuum controled by-pass valve. You will also need a pressure bypass valve (blow-off) valve to control transient pressures. When you rev the engine and close the throttle, pressure spikes of 30-40 psi will blow hoses.

If you do not have a wide-band furel air gauge, you need to get one. Running boost requires more fuel than the stock injectors can provide. I ended up with a complete digital engine management system. Here is some old info on my project: http://members.cox.net/bettyv/16v/jim_16v.htm

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